[Presto]

HTPCs are just a PC that's hooked up to the Home Theatre. Usually, it'll be running Windows, but any OS can be used. Most people will use front-end software, like XBMC, to manage and play their media.

AppleTV, WDTV, Boxee, etc... are considered media streamers, and run their own OS. They're a good, low-cost solution, and most people would be happy with them. I went the HTPC route for versatility. Also, anything that be viewed on a PC, can be viewed on the HTPC. IE: I don't need Hulu Plus to be able to watch it on my big screen, since it considers the HTPC a normal desktop.

No Cinavia issues. In fact, it's the first time I heard of that, and had to Google it.

Basic setup is just like setting up a normal desktop, except you'd connect it to your living room LCD for video, and your receiver for sound.